Electric arc smelting furnaces are used to manufacture steel from scrap metal. The scrap metal is heated to a melting temperature, such that the molten steel can be collected and processed for further use.
The melting process imposes thermal, chemical and mechanical stresses on the furnace. Consequently, the furnaces must have structural integrity to ensure safe operation and production. Frequent maintenance schedules must be maintained on the furnaces, thereby making recycling of steel very costly.
In an effort to alleviate the stresses, and to lower the operating cost of recycling steel, liquid cooling systems have been installed on electric arc furnaces. One such cooling system is disclosed in U.S. Pat. No. 4,207,060 which utilizes a series of cooling pipe coils. Generally, the coils are formed from adjacent pipe sections with a curved end cap welded to the ends of adjacent pipes to form a serpentine path for a liquid coolant flowing through the coils. This coolant is forced through the pipes under pressure to maximize heat transfer.
Another cooling system is disclosed in U.S. Pat. No. 4,119,792 which utilizes cooling boxes, rather than coiled tubes. The cooling boxes may include internal channels to direct cooling water from the bottom to the top of the coiling box.
The cooling coils and cooling boxes of the prior art are typically manufactured of steel or copper. While copper has better heat transfer properties than steel, copper is much more expensive than steel. Copper also does not have the structural strength of steel. Furthermore, cast steel panels are subject to mechanical-thermal stresses due to uneven cooling across the face of the panel. Coiled steel tubes or pipes are subject to heat stress cracking, particularly at the bends or end caps of the coils.
Electric arc furnaces are being used at hotter temperatures and faster production times, which increases the heat cycle time, thereby increasing failures from stress in both coiled tubes and cast panels. While copper resists such stresses is better than steel, the cost of manufacturing such copper pipes and panels is expensive, compared to the cost of steel pipes and panels.
Accordingly, a primary objective of the present invention is the provision of a bi-metal panel having an inner copper face and an outer steel face for use in an electric arc furnace.
Another objective of the present invention is the provision of an electric arc furnace cooling panel having a bi-metal construction utilizing copper only on the inner heat transfer surface of the panel.
A further objective of the present invention is the provision of an improved cooling panel for an electric arc furnace having a smooth, thin, inner copper wall.
A further objective of the present invention is the provision of an improved cooling panel for an electric arc furnace which produces a uniform slag layer, thereby reducing the heat flux required to be removed from the furnace by the panel.
Another objective of the present invention is the provision of an improved cooling panel for an electric arc furnace which is economical to manufacture, thermally efficient and effective, and having minimal maintenance requirements.
A further objective of the present invention is the provision of an electric arc furnace cooling panel which is resistant to heat related stresses.
Another objective of the present is the provision of a cooling panel for an electric arc furnace that can be used in the side wall of the furnace or in the roof of the furnace.
These and other objectives become apparent from the following description of the invention.